I know that merging accounts with different e-mails is hard. The question is can I go and change the e-mail on the account to match to resolve this? Or do I have to create a new account period, so that all of my projects have the same e-mail?

You got the answer in the WCG-forum already.

If you are talking about merging two separate accounts at a project, that will depend on each project's policies. While it's not impossible, I don't know of any projects that do this.

Right, if your already using an e-mail address and try to change another account to that address you should get a message that say's that e-mail address is already being used. Unless you can get the project Dev's to Merge the Account's I don't think you can on your own ...